People’s thoughts on TR4

[stuart]

4 minutes ago, roy53 said:

Do not all live axle 4A have an IRS chassis ?

Done for the USA market for some reason .

Roy

Yes they do, The US market was hesitant to accept the IRS setup after loving the TR4 so much and so Triumph came up with the live axle version with minimal modifications (different shock drop links and a special bracket for the front of the spring attached to the outer trailing arm bolt holes, mountings for the rear shackles and slightly longer shackles) On the US market it was also a few hundred dollars cheaper too.

Stuart.

[Lo100469]

I feel bad to have an IRS now.... seriously the TR4 has a stronger chassis as it is a simpler ladder design.  I did not find one and went for an IRS.  Also some fit a suspension conversion at the back of the IRS that if not done right can crack the frame.  i think everyone agrees that the TR4IRS with a different back end that is more prone to rust and cracks and requires more attention.  The US requested a live axle on the later chassis so you do not retain the strength of the former TR4 chassis, it is a bit the worse of both worlds.

Laurent

[Motorsport Mickey]

" it is a bit the worse of both worlds."

Seriously ?  I doubt you'll find many instances where a TR4a chassis has suffered a chassis failure caused by corrosion. 

Read the attached thread here on the Forum, then try and convince me the independent suspension choice is for the better. 

 https://www.tr-register.co.uk/forums/index.php?/topic/71509-tr4a-rear-hubs/

We have lots of other posts showing rear hubs breaking and stub axles snapping, all available to review in our search box. Did I| mention "crack testing," ? it has been investigated but apart from the hubs which snap in half where the cracks are inside them and unreachable for testing, people who have made a career out of NDT (Non destructive testing) say these stub axles go from uncracked to cracked and unsafe in very short order, and microcracking hidden behind bearings is again unreachable.

Now this is not to say a "live" axle car cannot crack and snap a halfshaft but try searching for that in the search box or any other method (Google) of searching the Forum and I would doubt you'll find many or even any. I believe have had a live axle car snap an axle when used for competition but I haven't details of it and I think that would be one against the many failures of IRS cars and also ANY Triumph car which uses this "Innsbruk" rear suspension system across the range of TRs, Triumph Stags and the large Triumph saloons.

Teeth sucking stuff.

Mick Richards

Edited October 13, 2023 by Motorsport Mickey

[BlueTR3A-5EKT]

My youthful money spinner was breaking TR’s and selling on certain parts.   Body panels, Surrey tops,  power units, gearbox WITH overdrive, axles, and  some electrical items like switch gear.   Instruments and wiper motors were sold for the core units to be rebuilt.

Of the many vehicles I broke I would say 75% were IRS cars that failed MOT tests for extensive chassis and body rust which made them beyond economic repair.

 

[stuart]

1 minute ago, BlueTR3A-5EKT said:

 

Of the many vehicles I broke I would say 75% were IRS cars that failed MOT tests for extensive chassis and body rust which made them beyond economic repair.

 

Yep.

Stuart.

 

[Michel Higuet]

16 minutes ago, BlueTR3A-5EKT said:

My youthful money spinner was breaking TR’s and selling on certain parts.   Body panels, Surrey tops,  power units, gearbox WITH overdrive, axles, and  some electrical items like switch gear.   Instruments and wiper motors were sold for the core units to be rebuilt.

Of the many vehicles I broke I would say 75% were IRS cars that failed MOT tests for extensive chassis and body rust which made them beyond economic repair.

 

England is the best country for chassis and body rust, my TR4a come from California...   :-) 

[Andy Moltu]

4 or 4A? Appearance is a matter of personal taste.

Handling - the racers seem to prefer the live axle 4 over the 4A. Is that because of handling or homologation?

Ride - the IRS have it for road  use but again the differences are marginal.

The hood arrangements are different but who drives with the roof up by choice?

The engine capacity varies but many cars have had their engines rebuilt, frequently with larger capacity. Most rebuilds are using 89mm pistons and liners these days.

I would say go for the car with the best body and chassis as that’s the expensive bit. Most other jobs are within the skills of someone who can follow a manual.

 

[Chilliman]

2 hours ago, Andy Moltu said:

Handling - the racers seem to prefer the live axle 4 over the 4A. Is that because of handling or homologation?

 

In my case - handling

[Lo100469]

Mick,

Is the  4A chassis not similar for both live axle and IRS models?  I always thought they took an 4A IRS chassis and fitted the live axle only for the US market.  My only comment is to say that this chassis remains weaker than the original 4.  Why would a 4A chassis rust less or flex less on a live axle car? 

You are of course right about rear hubs issues for IRS cars, that is a real concern and i had to change mine to the upgrade ones, that was not cheap.

Cheers,

Laurent

[Motorsport Mickey]

13 minutes ago, Lo100469 said:

Mick,

Is the  4A chassis not similar for both live axle and IRS models?  I always thought they took an 4A IRS chassis and fitted the live axle only for the US market.  My only comment is to say that this chassis remains weaker than the original 4.  Why would a 4A chassis rust less or flex less on a live axle car? 

You are of course right about rear hubs issues for IRS cars, that is a real concern and i had to change mine to the upgrade ones, that was not cheap.

Cheers,

Laurent

I don't have a 4a and so can't give definitive details upon chassis differences between live axle and IRS models, (Stuart will probably know chapter and verse on that) however the 4a chassis because of it's bell like central shape and bridge to carry the diff on the IRS and the flexing around there, will suffer more from stress corrosion around the metal in that "T shirt" covering area (it's the shape) as shown in Stuarts photos. The added thicknesses of metal one on the other there also traps moisture and again causes corrosion. Depending upon how the outer axle ends attach to the springs will feed road stressing into the chassis but likely to be less than on IRS, Stuart will hopefully give his feedback on that.

Mick Richards

[ntc]

35 minutes ago, Motorsport Mickey said:

I don't have a 4a and so can't give definitive details upon chassis differences between live axle and IRS models, (Stuart will probably know chapter and verse on that) however the 4a chassis because of it's bell like central shape and bridge to carry the diff on the IRS and the flexing around there, will suffer more from stress corrosion around the metal in that "T shirt" covering area (it's the shape) as shown in Stuarts photos. The added thicknesses of metal one on the other there also traps moisture and again causes corrosion. Depending upon how the outer axle ends attach to the springs will feed road stressing into the chassis but likely to be less than on IRS, Stuart will hopefully give his feedback on that.

Mick Richards

Then ask Stuart to post a picture of his car underneath.

[ricky30dk]

Thank you all for your advice on correcting my torque-steer - which for me occurs when accelerating or decelerating sharply (not braking, just taking the foot off the accelerator). I have deep dish springs and replaced the metallastic bushes during the refurbishment. I will now try tightening up the U-bolts further, checking the locating hole in the axle bracket for slotting and consider poly bushes at the front too. 

[Charlie D]

52 minutes ago, ricky30dk said:

...occurs when accelerating or decelerating sharply (not braking, just taking the foot off the accelerator)...

Exactly the same as I had. (Also had it happen on a Landrover Discovery) As I mentioned all I needed to do was tighten the U bolts, but as Bob says it could be the location hole as elongated. Whatever it is worth fixing sooner rather than later., as it will only get worse. For anyone who has never experianced it, it's quite frightening when it first happens.

Edited October 14, 2023 by Charlie D

[MichaelH]

TR4 driveshaft failures: I have seen two TR4s roll as a result of Driveshaft failures, both racing cars and both with early driveshafts: the American TR4As with solid axles had better quality haft shafts with collar rather than the stress riser shape of the early cars. One solution (the Americans had their own) was the BPA Driveshaft actually developed for the Aston Martin DB4 Racing cars. Expensive but cheaper than a body work roll over see photos

 

MichaelH

Lebro managed to get the pictures the right way up see next entry

 

Edited October 14, 2023 by MichaelH

[Lebro]

  

[Chilliman]

7 hours ago, MichaelH said:

the American TR4As with solid axles had better quality haft shafts with collar rather than the stress riser shape of the early cars.

I am yet to be persuaded that this is the case, for two reasons:

1) At the time these axles were being produced the UK car market was struggling & were cutting costs wherever they could so it seems to me they would have saved a significant amount of money by using a smaller stock bar & fitting a simple collar rather than machining down a really large piece of stock bar to create the classic tulip shape.

2) Of all the broken rear half shafts I've seen - none of them were broken at the point of the so called stress riser in front of the tulip shape. They were predominantly broken as shown in your photo.

As always I'm happy to be proven wrong but everything I've ever heard about American live axle half shafts has been anecdotal. As one of my good friends says it's a case of 'the emperors new half shafts'

 

 

[BlueTR3A-5EKT]

5 hours ago, Chilliman said:

I am yet to be persuaded that this is the case, for two reasons:

1) At the time these axles were being produced the UK car market was struggling & were cutting costs wherever they could so it seems to me they would have saved a significant amount of money by using a smaller stock bar & fitting a simple collar rather than machining down a really large piece of stock bar to create the classic tulip shape.

2) Of all the broken rear half shafts I've seen - none of them were broken at the point of the so called stress riser in front of the tulip shape. They were predominantly broken as shown in your photo.

As always I'm happy to be proven wrong but everything I've ever heard about American live axle half shafts has been anecdotal. As one of my good friends says it's a case of 'the emperors new half shafts'

 

 

Interesting.

From a parts man’s point of view I was surprised when I saw my first TR4A rigid axle half shaft.  I thought.   Cheapskates!

Then we ordered in some halfshafts for Dolomite Sprint, and lo and behold they had the same arrangement of a steel sleeve on a shaft rather than the Girling axle 3/3A/4 forged tulip shape we all remember.

I think you are right it is an economic choice.   That said there may be a strength issue here too

[Neilson]

Hi all,

OK, I’ve heard back from the seller on an issue that a few of you spotted regarding the floor to sill reinforcement brackets. He said…

The angle body mounts (floor to sill brackets) are not on the car, but all new inner and outer cills were welded to the new floors, also the boot flooring is new.

There was no hidden rust covered up on the car whatsoever. I have been over to see the TR specialist today, and having it on the ramp he assured me that there is no problem with the missing angle brackets.

It’s also an original British car.

What does everyone think, could I get the brackets added later?

Thanks

[ntc]

Number one there is no inner sills they are part of the floor pan so should not be welded.

[Neilson]

16 minutes ago, ntc said:

Number one there is no inner sills they are part of the floor pan so should not be welded.

Thanks for the update. Can I add the reinforcement brackets if I purchased the car, or should this have been done during the restoration?

Thanks

[Neilson]

Also, the chassis number is: no ct20219, engine: ct20478e, body number: is29524CT - do these all seem good?
There’s no heritage certificate - is this an issue, or can I apply for one?

Thanks everyone for your input!

[roy53]

When he says inner cill ,that is the part above the floor no 93 in moss book so not relevant.

Never seen a car without these brackets fitted

Roy

[Neilson]

24 minutes ago, roy53 said:

When he says inner cill ,that is the part above the floor no 93 in moss book so not relevant.

Never seen a car without these brackets fitted

Roy

Thanks Roy,

Can they be fitted at a later stage quite easily?

Best

Neil

[rcreweread]

The inner part of the cill structure below the floor is actually part of the floor pan pressing.I sus pect this was rotten but rather than replace the whole floor pan, this lower part has been cut off and piece of flat steel welded in place. In practice, if this has been done well with sound spot welds or plug/seam welds, in my view this is OK, but could weaken the structure a little . Just reread thread from start and can see it has had new floor pans, so the dealer is simply misdescribing what is actually there - this makes it even more surprising that the floor brackets have been omitted - it's not as if they are not available.

What isn't OK is leaving out the under floor strengthening brackets, which both strengthen this whole area and spread the load onto the chassis mounting - given that this arrangement is largely what holds the body onto the chassis, their omission could have serious consequences in the event of an accident. The shape of the brackets is such that you can't slide them into place as they  are - I suppose you could flatten out one side so you could slide it in and then refold the flattened out side. You then need to weld the bracket to the inner cill/floor pan , the former going to be difficult to get full access because of the chassis bracket. Obviously you would have to remove the floor to chassis mounting bolts and the rubber/metal/canvas pads first, and then repack afterwards ( assuming these are all there  - have you got a photo of this area?

The chassis and engine numbers look close enough to be original to each other, but the body number doesn't match, unless the 2nd digit has been mis stamped as a 9 instead of a 0 - you could easily resolve this by getting a Heritage Certificate ( from the British Motor Museum)

Hope this helps

Cheers Rich

Edited October 16, 2023 by rcreweread

[stillp]

18 minutes ago, Neilson said:

Thanks Roy,

Can they be fitted at a later stage quite easily?

Best

Neil

No, and their absence would make me question what else has been left out.

Pete